1. Field of the Invention
This invention relates to a monoclonal antibody and a cell line capable of producing the same which may be used to detect various crack cocaine metabolites in a sample. This invention also relates to immunogens in the form of crack cocaine conjugates used to evoke an immune response in animals.
2. Background
When cocaine enters the human body it is quickly broken down into various metabolites. These metabolites are longer lived than the cocaine itself and thus may be assayed to determine if an individual has previously ingested cocaine. Various methods have been utilized to determine whether these metabolites are present in a sample, for example, immunoassays and gas chromatograph/mass spectrometer (GC/MS).
Gas chromatography/mass spectrometry is a highly sensitive and specific diagnostic tool for determining the presence and concentration of chemicals in a sample. However, it is expensive, time-consuming, and labor intensive; therefore, immunoassays, which are cheaper and quicker, are commonly used as an initial screening stage. Those samples which test positive using an immunoassay are frequently confirmed by gas chromatography to verify the presence of the metabolites.
Immunoassays detect their target chemical by utilizing antibodies which are raised to be specific for the particular chemical or closely related compounds. These antibodies have the ability to selectively bind to the chemical(s) in question while generally not binding to other chemicals in the sample. Thus, antibodies are quite useful in detecting the presence of chemicals in a sample even at nanogram per milliliter levels.
Antibodies specific for cocaine metabolites have previously been developed and produce highly sensitive diagnostic tests for detecting cocaine use. Currently available tests utilize monoclonal antibodies with a high affinity to a specific metabolite of cocaine, benzoylecogonine (BE); BE is used in these tests because it is the metabolite with the highest concentration several days after cocaine ingestion.
In the 1980's a smokable form of cocaine, “Crack” cocaine, became increasingly prevalent. Crack cocaine is a highly potent and addictive substance. Smoking, chemically referred to as pyrolysis, of crack cocaine produces distinctive metabolites such as anhydroecgonine methyl ester (AEME) and ecgonidine (ECD) which are not present in users of the powdered or injected forms of cocaine.
The addiction associated with crack cocaine and its particular central nervous system distribution leads to clinical complications that are different from powdered or injected cocaine use. In addition, criminal penalties for crack cocaine are potentially different than those of the powdered or injected forms. Despite the need for a test able to discriminate between the use of crack cocaine and cocaine's other forms, until now, no immunoassay or monoclonal antibody was able to selectively detect the use of crack cocaine versus the powdered or injected forms of the drug. Commercial immunoassays can detect only BE which is produced in both powdered and crack cocaine users. As there are specific clinical and legal implications for crack cocaine use, the need for monoclonal antibodies capable of distinguishing between the use of crack cocaine and the powdered or injected form, is evident.